Incandescent electric lamp.



No. '787,428'. PATENTED APR. 18, 1905.

- I'. H. BLACKBURN.

INGANDESCBNT ELECTRIC LAMP.

APPLICATION FILED JAN. 6. 1904.

,my 9d.

UNITED STATES Pari-nf FRANK H. BLACKBURN, OF FOSTORl'A, OHlO, ASSlG-i ORTO @dit NATONAL ELECTRIC LAMP COMPANY, OF CLEVELAND, OlilfO, ACORPORATON OF NEW JERSEY.

INGANDESCNT ELEOTFHM;

Application led Janna-ry 6, 3.904. Serial No. 1821,88?.

To all whmn il; may concern:

Be it known that I, FRANK H. BLACKBURN,

a citizen of the United States, residing` at Fostoria, in the county ofSeneca and State of Ohio, have invented a certain new and useful Improvement in Incandescent Electric Lamps, ot which the following is afull, clear, and exact description, reference being had to theaccompanying drawings. v

This invention is a so-called tipless incandescent lamp-that is to say,an incandescent lamp which has no visible tip.

The tip on an incandescent lamp is the pointed projection which remainsattached to the lamp after the exhaustion-tube has been fused olf, whichtip seals the hole through which the air is exhausted. Ordinarily thesetips are at the Xtreme outer end of the bulb. `Wher ever they are, if inthevisible part of the bulb, 2O they are objectionable for many reasonswell understood in this art. .Many elorts have been made to do away withthe visible tip; but such eorts have heretofore not resulted in anysatisfactory practical construction. in

. a practical construction the exhaustion-tube,

of which the tip is the remains, must be accessible throughout itslength during the manufacture of the lamp, so that it can be repairedwhen broken, and it is very liable to be broken during the repeatednecessary hand ling. Said exhaustion-tube must not be attached so nearanother seal that the glass at the point of attachment is under straindue to the other seal, because thereby the liability to breakage' ismultiplied. -It must not require the reduction in the size of the bulbor any variation from the standard size of the lampbase.

A lamp constructed according to the inven- A4C* tion herein describedhas all ot the necessary characteristics above referred to, and,moreover, it costs no more to make the lamp than it does to make theordinary lamps in common use with the Avisible tip.

The invention in its entirety consists in incandescent lamp having` itstip projecting,r out from the side of the neck of the bulb and covered,concia. ed, protected by the shell of the lamp-base;. and it consi ts,further, in certain details of construction, 'to be herein- SO afterdefinitely pointed out.

n the drawings, Figure l is an elevation o'tf a lamp-bulb, showing itscondition in an early stage in the manuiacture ot' a lamp in accordancewith this invention and having the exhaustion-tube secured thereto. Fig.2 is a similar View of the lamp after the stern has been inserted intoand sealed to the bulb. Fig. 3 is a similar view ot' the lamp after theexhaustion-tube has been fused of? and the opening` sealed, but beforethe base has been applied; and Fig. i is similar View of the completedlamp, one side ot' the neck and ol' the base being in section.

Referring to the parts by letters, A repre sents the lamp-bulb of'Familiar outline and oi' regular size, (t being the neck thereof.

B represents the stem, whose daring; lower edge is sealed to the lowerend or` the neck.

D represents the base oi' the lamp, having' '.70 the usual threadedshell, which is intended to be secured upon the neck in the usual way.

in that part of the'neck fr. which will be -oraced by and covered by theshell (l of the e is a perforation (nl, which is preferably 7 ned beforethe stem B is sealed to the lower end of the neck. This perforation isin the best construction, as shown, formed in a portion t3 oi said neckwhich is depressed below the adjacent surfaces, said depression being,asshown, annular, extending entirely around the neck. Theexhaustion-tube E is fused to the neck over this perforation, as shownin Fig. 3, and then the stem is sealed terfere with the applic in in'the usual way of the standard base The shell Z of the base covers,conceals, and protects the tip'.

The described lamp is tipless in the ordinary sense and is quite asstrong and no more expensive than the ordinary lamps.

1. In an incandescent lamp, a bulb having a depression in its neck, andthe tip which seals the air-exhaustion hole projecting from saiddepressed portion.

2. In anincandescent electriclamp, the combination of a bulb having aneck and a tip projeeting laterally out from said neck, with a. metallicbase having a shell which embraces said neck and conceals and protectssaid tip.

3. In an incandescent electriclamp, the combnation of a bulb having adepression in its neck and the tip projecting out from said depresseduportion, with a base having a shell which embraces said neck and coverssaid depressed portion thereof and thereby conceals and protects saidtip.

In testimony whereof 1 hereunto alix my 20 signature in the presence oftwo witnesses.

FRANK H. BLACKBURN.

Witnesses:

. A. H. WINsLow,

E. J. KULAs.

